# Describe single-replacement and double-replacement reactions.

mkcapen1 | Middle School Teacher | (Level 3) Valedictorian

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A single placement reaction occurs when two elements are combined creating an oxidation reduction type of reaction.  It is also called a single displacement reaction.  In the process an ionic compound reacts with a free element to create a different ionic compound.

1. d +   ce  ®   c +   de
2. (element d is the  ionic compound)
3. (c is the positively charged ions)
4. (e is the negatively charged ions)
5. It is called a single replacement because it looks like d is replacing c

In a Double Placement Reaction occurs when two ionic compounds are mixed together.  The ionic compounds split apart separating their  anions and cations.  A checmical reaction occurs resulting in a product that can ot be reversed/separated.

maria-vivanco | Student, Grade 11 | (Level 1) Valedictorian

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When a single replacement reaction takes place, the element that is separate to the compound would combine with the opposite element of the compound that its getting added to.

AX + Y = AY +X

On the reactant side, y is the opposite of x. Let's suppose that the equation is

2Ag + CuSO4 = Ag2SO4 +CU

Ag has a positive charge because it is a metal

SO4 is a negative ion, it's sulfate. They combine because they are opposite and combine to make a compound. Cu becomes separate.

Double Replacement:

Double replacement based on the same concept. Except that the reactant has two compounds instead of one. The same concept applies, the positive element combines with the negative element on the seocnd compound. And the negative compound combines with the positive of the second.

For example:

2NaI + CaCL2 = 2NaCl + CaI

Na (positive) would combine with cl (the negative element in CaCL2)

I (negative) would combine with Ca (positive)

givingiswinning | Student, Grade 10 | (Level 1) Valedictorian

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Single Replacement

A + BX ---> B + AX

Double Replacement

AX + BY ---> BX + AY

atyourservice | Student, Grade 11 | (Level 3) Valedictorian

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Single Replacement:

H + XI ---> I + XH

Double Replacement:

XI + BK ---> BI + XK

parama9000 | Student, Grade 11 | (Level 1) Valedictorian

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Yes, I do agree with you Yojana. The simpler way to express the concept of single replacement and double replacement would be your way. For single replacement, it would be element, compound, transformed to element, compound. For double replacement, it would be all compounds, as from the very start, they are all compounds.

Yojana_Thapa | Student, Grade 10 | (Level 1) Valedictorian

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Single Replacement

A + BX ---> B + AX

Element, compound, element, compound

Double Replacement

AX + BY ---> BX + AY

Compound, Compound, Compound, Compound